A quantum algebra method for deducing the symmetries of discrete equations
on uniform lattices is proposed. In principle, such a procedure can be appl
ied to discretizations in a single coordinate (space or time) and the symme
tries obtained in this may are indeed differential-difference operators. Fi
rstly, the method is illustrated on two known examples that have been also
analysed from the usual Lie symmetry approach: a uniform space lattice disc
retization of the (1 + 1) free heat-Schrodinger equation associated to a qu
antum Schrodinger algebra, and a discrete space (1 + 1) wave equation provi
ded by a quantum so(2, 2) algebra. Furthermore, we construct a discrete spa
ce (2 + 1) wave equation from a new quantum so(3, 2) algebra, to show that
this method is useful in higher dimensions. Time discretizations are also c
ommented.